In an aircraft with retractable nose landing gear, this gear is generally housed in a landing gear bay or box secured to the aircraft fuselage around an opening through which the landing gear can be lowered from the bay and retracted thereinto. Moving doors close this opening in the flight configuration and open downwards when the landing gear is lowered.
In such a conventional configuration, the nose landing gear bay is subjected internally to atmospheric pressure and thus forms an enclave within a pressurized zone of the aircraft. Its walls are reinforced by a framework in order, firstly, to withstand the loadings transmitted by the landing gear and secondly to form a pressure barrier.
Patent FR 2 910 875 discloses an aircraft nose structure of the type comprising a fuselage and a pressuretight bulkhead fixed at its periphery to the said fuselage and transversely dividing the said fuselage into a pressurized zone and an unpressurized zone in which to accommodate retractable nose landing gear. According to that patent FR 2 910 875, this bulkhead is substantially planar and extends, on one side, upwards and towards the nose of the fuselage from the front edge of a floor of the pressurized zone and, on the other side, downwards and towards the rear of the fuselage from this front edge of the floor, under the latter. In such an arrangement, the unpressurized housing accommodating the nose landing gear is delimited between part of the pressuretight bulkhead, lateral walls of the fuselage and a front panel which separates this housing from an unpressurized nose containing electronic equipment such as a radar. A configuration of this type makes it possible to reduce the mass of the aircraft nose structure by comparison with a conventional configuration.